The project, a take on Erle Stanley Gardner’s classic character, to be portrayed by Robert Downey Jr., originally was set up for development at the premium cable network a year ago with True Detective creator Nic Pizzolatto on board to write. Pizzolatto since has focused his attention on True Detective, which is gearing up for a formal third season greenlight after recently tapping Oscar winner Mahershala Ali to star in the new installment.

Fitzgerald, who is under an overall deal at HBO, and his frequent collaborator Jones will now take on writing duties on the Perry Mason reimagining series as it goes through development.

The character of Perry Mason, an unorthodox investigator/defense attorney, was created by Gardner in the early 1930s. Mason has been featured in more than 80 novels and short stories, a radio series and six feature films in the 1930s, a comic strip in the early 1950s, an Emmy-winning TV series starring Raymond Burr that ran from 1957-66, the short-lived New Perry Mason TV show from 1973-74, and more than 20 made-for-television films that aired during the 1980s and ’90s.

Team Downey (Downey Jr. and his wife, Susan) originally had a Perry Mason feature reboot set up at Warner Bros. six years ago with Downey Jr. attached to star.

This would mark Iron Man star Downey Jr.’s biggest TV series commitment since his role on Fox’s Ally McBeal.

Fitzgerald and Jones began their careers as writers on Showtime’s long-running dark comedy Weeds starring Mary-Louise Parker. Their other joint series credits include Showtime’s United States of Tara, starring Toni Collette, and NBC/DirecTV’s Friday Night Lights. They also wrote and executive produced together the AMC pilot The Knifeman. Separately, Fitzgerald worked on NBC’s Prime Suspect, starring Maria Bello, and ABC’s Last Resort, Jones worked on HBO’s Boardwalk Empire, AMC’s Low Winter Sun, CBS’ Life In Pieces and Fox’s The Exorcist. Fitzgerald is repped by WME and the Shuman Co.; Jones is with CAA and the Shuman Co.